This is probably really stupid but why cant I bet 100 on a close sports game game for example and if I lose bet 200 on the next one, it’s 50/50 so eventually I’ll win and make a profit
In: 4566
Your expected profit just isn’t realistically worth it.
Say you start with betting $1 and you lose 5 times, until you win. In this case on the last bet you would be putting in $16 to win $32 dollars, giving you a profit of $16. However if you add up all the losses of the previous rounds, 1+2+4+8 = $15. Therefore your true profit is $1.
This method basically guarantees a $1 profit, but no one has infinite money and the chance you hit a bad streak is likely over time.
There is always the chance where you either come across a losing streak bad enough to deplete your entire bankroll, or/and require bet sizes large enough that the casino/sports book won’t accept them anymore.
Once that happens, the strategy falls apart and you’re left with a massive loss.
a) you don’t have infinite money
b) the odds are chosen to ensure that on average you always lose money
You can. But very, very, very quickly you will be into huge sums.
Even if you start at a single dollar, by 10 bets you’re into $1000.
So if you had started at $100, that’s $100,000 you’d be needing to find.
Sure, you might win one along the way but actually the odds aren’t even that great. Starting at 100, you’d be lucky to get past four or five such bets before starting to run out of money.
100… 200… 400… 800… 1600…
50% chance you lose that 100 on the first bet.
If you pass that, 50% chance you lose the 200 (so you’re now at three quarters failure chance, one quarter success chance). By just 5 bets, you’re at 50% * 50% * 50% * 50% * 50%…. which is less than 3% chance of success (so 97% of people who try would never even get that far). Then 1.5%. Then 0.75%. and so on.
Eventually you’ll LOSE, guaranteed, and in a very short space of time, with the vast probability being that will happen before you see any significant gain.
It’s literally a prime example of the gambler’s fallacy. And if you don’t understand how/what/what that means, I suggest you never gamble even a penny.
This is known as the [Martingale system. ](https://en.m.wikipedia.org/wiki/Martingale_(betting_system)) It is prevented in a couple of ways. You would only end up winning as much as your first bet. You will eventually run out of money on a bad streak. And before that, you will run into the maximum bet.
It is often used in roulette for betting red or black, which is almost 50:50, but not quite because of 0 and 00. If $25 is the minimum and $500 is the maximum bet then you only need to lose 5 times in a row to be over the max, 25-50-100-200-400
This is referred to as a Martingale system in gambling and it will always fail you in one way or another. Not because the math doesn’t work, in theory, but because of reasons a couple others have mentioned —
1. You will encounter a losing streak that requires you to wager more than you have.
2. Even if you have an arbitrarily large sum to wager after a long losing streak, all casinos and bookies have limits on wager sizes they’ll accept so your infinite stack of cash becomes more of a risk to them than they’re willing to accept.
On the topic of losing streaks, I heard a statistics professor talking about a coin flipping exercise she does with her students each semester. She has one group “randomly” choose a string of 100 coin flips, e.g. where they just make up results and write them down — pretending to replicate a coin flip situation.
The second group is instructed to actually flip a fair coin and record the real results.
Both groups record their results on a whiteboard. The professor leaves the room during this process and doesn’t know which set of results is the real one until looking at them closely, and pretty much always identifies which is real and which is fake — with far greater than 50% accuracy.
How does she do it? The fake group tried to make it look real by having very few, if any long strings of the same result (e.g. there are very few HHHH type sequences — they tried too hard to make the coin look … too fair, for lack of a better term).
But the professor knows, mathematically speaking, the chances of having a string of, say 6+ of the same result in a row with a fair coin over the course of a hundred flips actually quite high. Much higher than our intuition suggests. So she looks for which set has the largest run of the same value, or the set which has the most runs of 4-5 matching values in it.
All that to say, the probability of a crushing losing streak with your Martingale strategy is a lot higher than you think.
Doubling gets really out of hand really quickly and your winnings never exceed your original bet, making the risk not worth it.
$1, $2, $4, $8, $16, $32, $64, $128, $256, $512, $1024, $2048, $4096, $8192, $16384, $32768, $65536.
The trick here is that if you’re winning a 2:1 payout, your total winnings _never exceed $1_.
It’s called martingale and it doesn’t work for 2 reasons:
1- casinos have minimum and maximum bet sizes that prevent you from doubling the bet forever.
2- 50% pretty much guarantees that you will eventually get both results but you can still get very long losing streaks and you would need a large enough bankroll to cover it. For a losing streak of 10 times you need to have more than 1000 times you bet size in the bank and you will run into a 10x losing streak before you win 1000 times.
You’re not taking into account the bookie/house juice that you pay on each bet. No organized gambling game is 50/50. That’s why you have green numbers on a roulette wheel.
Casinos and bookies LOVE people who think this works. In reality,
1: The amount you need to bet quickly grows astronomical. Try this very often and you will hit a point at which you can’t cover your next bet, at which point half your money, at least, is gone. Do it too often and you WILL lose everything you have.
2: Even if you have the money, no-one is going to allow you to keep doubling your bet indefinitely. Casinos, for example, have table limits. Hit that limit and, again, you’ve lost everything you’ve bet (which will be at least the table limit).
3: If you DO eventually win, your total gain will be – your initial stake. And to get that, you will often have risked many, many times as much.
**tl;dr:**
It’s a fine way to go broke very fast.
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